Moacir

This plugin allows you to reduce shipping rate dynamically according to products in the customer cart.
Each product can donate a value to reduce shipping rate, so if there are two products in the cart, one with 2.00 of discount and another with 3.00 of discount, if the shipping rate is 17.00 this plugin will reduce shipping rate to 12.00.
The idea behind this plugin is to improve your sales by transferring the shipping rate to product price avoiding customer to abandon on the checkout/cart page.

WooCommerce Shipping Discount

solvenium

personaldiscount

This plugins enables you create links with a coupon code that will be applied automatically.
If your shop URL is <code>https://shop.example.com</code> then you can add a coupon code in a query parameter like this <code>https://shop.example.com?coupon=WELCOME10</code>.
You can add the coupon code to any URL pointing to a page within yor WooCommerce store. It can be a homepage, product, category, cart, checkout or any other page.
<ul>
<li><code>https:\\shop.example.com\product\invisible-watch?coupon=vip-x4tz8</code></li>
<li><code>https:\\shop.example.com\product-category\new-arrivals?coupon=HELLO-4M1GO</code></li>
<li><code>https:\\shop.example.com\product-category\new-arrivals?coupon=HELLO-4M1GO</code></li>
</ul>
Example use case
A perfect case for Woo Coupon URL is when you want to offer a discount to your newsletter subscribers. 
Normally, you’d append a coupon code to the email, and your customers would need to copy and paste the code. 
With Woo Coupon URL you can now send a link with the discount code that will be applied when your customers click on the link.

Woo Coupon URL

Attach a coupon code to your URL and apply it automatically to the cart.

WooCommerce Shipping Discount vs Woo Coupon URL